1. Field of the Invention
The present invention relates to an electrical adapter. In particular, the present invention relates to an adapter for a vehicle cigarette/cigar lighter socket.
2. Description of the Related Art
Many modern vehicles are provided with cigarette/cigar lighters. The lighter usually comprises a socket with a removable lighter cap. When activated, the current flows through a high resistance strip in the lighter cap causing a part of the cap to glow red-hot. A cigarette or cigar can then be lit from the glowing metal.
The socket can be used to power a large range of portable appliances, for example, mobile phones, car vacuum cleaners, lap-top computers, televisions, chiller cabinets, etc. Recently, the sockets on their own (without the cigarette lighter cap) have been provided in the back of MPV""s, off road vehicles, etc. Some appliances can be powered directly from the socket itself, others may require an adapter.
The adapter has a plug member which is inserted into the vehicle lighter socket. The plug member is elongate with a first contact at one end. The first electrical contact connects to a co-operating electrical contact at the base of the vehicle lighter socket. To ensure a good and reliable connection, it is preferable if the first electrical contact is mounted on said plug member such that the contact is resiliently biased towards the end of said plug member. In previous adapters, the first contact is electrically and mechanically connected to the remainder of the adapter via a spring.
This type of conventional spring contact creates a higher resistance and hence the adapter gets very hot. When the adapter is connected with heavy duty appliances, for example, spot-light, car vacuum cleaner, car heater, electrical heat pot, etc., an xe2x80x9covenxe2x80x9d effect will occur in the spring. The spring is typically made from mild steel.
The present invention provides an adapter for a vehicle cigarette lighter socket, the adapter comprising an adapter body, with at least one socket member and an elongate plug member attached to said adapter body, the elongate plug member having a first electrical contact at an end of said elongate plug member, the first electrical contact being electrically connected to the adapter via a ribbon form spring contact.
In the present invention, a ribbon form of spring contact (or plate-type contact) is used instead of a mild steel spring. The ribbon form contact is a ribbon of metal which is positioned so that it resiliently biases the first contact towards the end of the plug member. This ribbon form contact allows the adapter to have a lower resistance and hence less heat is generated. Therefore, adapters according the present invention are more stable in function and are more hard wearing.
The ribbon form contact is used to resiliently bias the first contact towards the end of said plug member. To do this, it is preferable if the first contact is mounted to the plug member via just the ribbon form contact. More preferably, the ribbon form contact is substantially s-shaped, the first electrical contact being mechanically connected to a wall of said plug member.
Preferably, the adapter comprises a fuse. If the adapter comprises a fuse, the socket member is electrically connected t o the plug member via the fuse. The fuse in the adapter is preferably 10 amp. This fuse may need to be replaced. Therefore, to aid replacement, it is preferable if the fuse is located on an outer surface of the adapter body.
As many appliances can be powered from the lighter socket, it is preferable if the adapter body comprises at least two socket members.
Therefore, according to a second aspect, the present invention provides an adapter for a vehicle lighter socket, the adapter comprising an adapter for a vehicle cigarette lighter socket, the adapter comprising an adapter body, with at least two socket members and a single elongate plug member attached to said adapter body, wherein the socket members are electrically connected to said plug member.
The single elongate plug member is for insertion into the single vehicle lighter socket and two appliances can n be powered from the first and second socket members. For example, one of the socket members could provide power to charge a mobile phone and the cigarette lighter cap could be fitted to the second socket member.
Of course, the present invention need not be limited to an adapter with just two socket members. Therefore, it may be preferable if the adapter comprises at least three socket members which are electrically connected to said plug member.
The actual socket acquired to provide power to a cigarette lighter cap is more complicated than a socket required to just give power. Conventional cigarette lighter sockets are a female type member with cylindrical walls and a flat socket base. The terminal is provided by part of the inside of the cylindrical walls and the second terminal is a piece of metal fixed at the bottom of the socket. The metal piece is shaped so that it extends partially up the cylindrical walls. The first and second terminals must be isolated from one another. Therefore, the conductor part of the cylinder wall must be cut so that it does not touch the second terminal.
This manufacturing process is time concerning and many of the appliances which can be run from a cigarette lighter socket cam make do with a much simpler design where all of the inside of the cylinder walls conducts and the second terminal is provided by a screw in the base of the socket.
Many lighter sockets are located in relatively awkward places in a vehicle. For example, they are often located close to and opposite the gear stick. Therefore, in some cases it is awkward to plug an appliance into the adapter. To overcome this problem, it is preferable if the plug can be moved relative to the adapter body.
Therefore, in a third aspect, the present invention provides an adapter for which a vehicle cigarette lighter socket, the adapter comprising an adapter for a vehicle cigarette lighter socket, the adapter comprising an adapter body, with at least one socket members and a single elongate plug member attached to said adapter body, wherein the at least one of the socket members is electrically connected to said plug member and said plug member is movable relative to said adapter body.
According to the first, second and third aspects of the present invention it is preferable if, the elongate plug member of the present invention is pivotally mounted on said adapter body. The adapter body can thus be pivoted to a more suitable position, for example pointing towards the passenger side footwell.
Alternatively the elongate plug member may be connected to the adapter body via a flexible lead.
It is preferable if the adapter is provided with an indicator which shows when the adapter can supply power. This is particularly useful for troubleshooting when an appliance which is plugged into the adapter doesn""t work. The indicator is preferably provided by an LED. If the LED is not lit then the user knows that there is a problem with either the adapter or the cigarette lighter socket itself as opposed to the appliance.